Input display

ABSTRACT

An input display is provided in the present invention. The input display includes a thin film transistor (TFT) and a light blocking layer. The TFT includes a low-field electrode, a high-field electrode connected to the low-field electrode with a connecting section, and a field-effect area positioned on the connecting section and connected to the high-field electrode, wherein a PN junction field is formed in the field-effect area when the TFT is switched off. The light blocking layer corresponds to the high-field electrode and hides the field-effect area from all incident light from the TFT.

FIELD OF THE INVENTION

The present invention relates to an input display, and more particularlyto an input display with a light detector array.

BACKGROUND OF THE INVENTION

Please refer to FIG. 1, which is a circuit diagram showing a lightdetector array of an input display according to the first prior art.

In FIG. 1, each unit of the light detector array includes a TFT switch.For example, the operation of the unit 11 in the position where thefirst read-out line intersects the first gate line is as follows. Whenthe light detector array is OFF, the gate line 1 is at low voltage. Thebody diode of the TFT is reversely biased so that there is no currentflowing through the TFT. When the gate line 1 turns to high voltage, thecurrent flows from gate line 1 through read-out line 1 to the readoutamplifier 12.

A photo-induced ON current occurs when the light is emitted onto theTFT. When the light is emitted onto the TFT, the photo-induced ONcurrent increases. Contrarily, when no light is emitted onto the TFT,the photo-induced ON current decreases.

When the input display with the light detector array is used, the touchof the display will influence the quantity of the incident light. Hence,which position of the display has been touched is able to be detected bysensing the quantity of the photo-induced ON current.

However, the drawback of the input display with the light detector arrayis the generation of the photo-induced leakage current, which alsooccurs when the light is emitted onto the TFT. The sensing and thedetection of the display are seriously held back by the photo-inducedleakage current.

To overcome the drawback, another implementation of the display has beenprovided. Please refer to FIG. 2, which is a circuit diagram showing alight detector array of an input display according to the second priorart.

In FIG. 2, each unit of the light detector array includes two TFTswitches. The unit 21 in the position where read-out line #1 intersectsgate line #1 is taken for example. The switch-TFT 11 is arranged forswitching and the photo-TFT 11 is arranged for detecting the intensityof the incident light.

In FIG. 2, the additional TFT is unnecessary to be emitted by theincident light, so the photo-induced leakage current is able to bedecreased. However, the increased number of TFT results in a lowerprocess yield.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an inputdisplay with a light detector array. The input display is able to befabricated in a higher aperture ratio and a higher production yield.Besides, the input display has enough photo-induced ON current when theTFTs are switched ON and has no photo-induced leakage current when theTFTs are switched OFF.

It is another object of the present invention to achieve theabove-mentioned object by appropriately designing a pixel unit with alight blocking layer which hides a field-effect area positioning on aconnecting section between a high-field electrode and a low-fieldelectrode and near the high-field electrode from all incident light fromthe pixel unit.

Preferably, the light blocking layer is a black matrix positioning on acolor filter or a metal layer positioning on a passivation layer in thepixel unit.

For the convenience of description, the embodiments of invention areillustrated in the structure of an n-type TFT. However, it is obvious toone skilled in the art to apply the technical characteristics of theinvention in the applications of a p-type TFT, a poly-TFT, and aTFT-LCD.

Please refer to FIG. 3(a) and FIG. 3(b). FIG. 3(a) is a cross-sectionalview of an n-type TFT of a light detector array. FIG. 3(b) is a diagramshowing the band of the n-type TFT when it is switched ON and OFFrespectively. In FIG. 3(a), the partial n-type TFT structure 30 iscomposed of a substrate 301, a metal layer 302, a gate insulator layer303, an amorphous silicon layer 304, a N⁺ amorphous silicon layer 305, adrain terminal 306, and a source terminal 307. The metal layer 302 isused as a gate terminal. The band diagram in FIG. 3(b) is shown withrespect to the dotted line drawn in FIG. 3(a).

In FIG. 3(b), a conduction band 311, a valence band 312, a channel 313,a drain terminal 314, a source terminal 315, holes 316, and electrons317 are symbolized in ON state 31, while a conduction band 321, avalence band 322, a channel 323, a drain terminal 324, a source terminal325, holes 326 and 328, electrons 327 and 329, and PN junction 320 aresymbolized in OFF state 32. The band diagrams are both drawncorresponding to the n-type TFT structure 30 in FIG. 3(a), so thehigh-field electrode is defined as a drain terminal and the low-fieldelectrode is defined as a source terminal.

When the TFT is switched ON in the ON state 31, the electrons 317 in thevalence band 312 are transferred to the conduction band 311 due to theemitting of the incident light (not shown) and holes 316 are generatedaccordingly. Then the electrons 317 move toward the drain terminal 314and the holes move toward the source terminal 315 due to the effect ofthe electric field, so that a photo-induced ON current (not shown)occurs between the drain terminal 314 and the source terminal 315.

When the TFT is switched OFF in the OFF state 32, the gate terminal (notshown) is connected to a low voltage. At this time, the bands 321 and322 in most of the area between the drain terminal 324 and the sourceterminal 325 are almost horizontal. That is, there is no electric fieldexisting in this area. The electrons 327 in this region will just betransferred from the valence band 322 to the conduction band 321 andwill be combined with the holes 326 repeatedly, even though the light(not shown) has been emitted onto the electrons (327). There is noassistance for the increase of the current. However, the current formedby an electric field, which occurs due to the transferring of the holes328 and the electrons 329, in a PN junction 320 existing near the drainterminal 324 constitutes the aforementioned photo-induced leakagecurrent.

According to the first aspect of the present invention, an input displayis provided. The input display includes a thin film transistor (TFT) anda light blocking layer. The TFT includes a low-field electrode, ahigh-field electrode connected to the low-field electrode with aconnecting section, and a field-effect area positioned on the connectingsection and connected to the high-field electrode, wherein a PN junctionfield is formed in the field-effect area when the TFT is switched off.The light blocking layer corresponds to the high-field electrode andhides the field-effect area from all incident light from the TFT.

According to the second aspect of the present invention, an pixel unitis provided. The pixel unit is composed of the TFT and the lightblocking mentioned in the previous paragraph.

According to the third aspect of the present invention, an eliminationmethod for a photo-induced leakage current of an input display isprovided. The elimination method includes steps of providing a thin filmtransistor (TFT) including a low-field electrode, a high-field electrodeconnected to the low-field electrode with a connecting section, and afield-effect area positioned on the connecting section and connected tothe high-field electrode, and hiding the field-effect area from allincident light from the TFT so that the photo-induced leakage currentproduced by a plurality of electrons influenced by the incident lightand the PN junction field formed in the field-effect area when the TFTis switched off is eliminated.

The every aspects of the present invention are suitable in theapplication of an n-type TFT, a p-type TFT, a poly-TFT, and an n-typetransistor or a p-type transistor with a channel made of semiconductorlayer, such as a-Si, poly-Si, single crystalline Si, III-V compounds . .. etc., or organic materials. Moreover, they are also suitable for thecombination of the fabrication process of a TFT-LCD to widen the utilityin the industrial application.

The foregoing and other features and advantages of the present inventionwill be more clearly understood through the following descriptions withreference to the drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing a light detector array of an inputdisplay according to the first prior art;

FIG. 2 is a circuit diagram showing a light detector array of an inputdisplay according to the second prior art;

FIG. 3 (a) is a cross-sectional view of an n-type TFT of a lightdetector array;

FIG. 3 (b) is a diagram showing the band of the n-type TFT along thedotted line of FIG. 3 (a) when the TFT is switched ON and OFFrespectively;

FIG. 4 (a) is an upper view of an n-type TFT of a light detector arrayaccording to the first embodiment of the present invention;

FIG. 4 (b) is a cross-sectional view showing the structure of FIG. 4 (a)along the dotted line;

FIG. 5 (a) is an upper view of an n-type TFT of a light detector arrayaccording to the second embodiment of the present invention;

FIG. 5 (b) is a circuit diagram showing the light detector arrayfabricated with the n-type TFT of FIG. 5 (a);

FIG. 6 (a) is an upper view of a TFT of a light detector array accordingto the third embodiment of the present invention;

FIG. 6 (b) is a circuit diagram showing the light detector arrayfabricated with the TFT of FIG. 6 (a)

FIG. 7 (a) is an upper view of an n-type TFT of a light detector arrayaccording to the fourth embodiment of the present invention; and

FIG. 7 (b) is a cross-sectional view showing the structure of FIG. 7 (a)along the dotted line.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for the purposes of illustration and description only;it is not intended to be exhaustive or to be limited to the precise formdisclosed.

Please refer to FIG. 4 (a) and FIG. 4 (b). FIG. 4 (a) is an upper viewof an n-type TFT of a light detector array according to the firstembodiment of the present invention, and FIG. 4 (b) is a cross-sectionalview showing the structure of FIG. 4 (a) along the dotted line. In FIG.4 (a), the TFT 40 is in the area surrounded by data line 1, data line 2,read-out line, gate line 1, and gate line 2 while the remainingcomponents in the area are omitted for the convenience of illustration.The TFT 40 in FIG. 4 (a) is implemented to correspond to the photosensitive switch TFT 11 surrounded by gate line 1, gate line 2, andread-out line 1 shown in FIG. 1. In the upper view of FIG. 4(a), only apart of the components of TFT 40 are shown. To clarify the structure ofthe TFT 40 of FIG. 4 (a), the description for FIG. 4 (b) is givenfirstly as follows.

The main object of the invention is to provide a pixel unit and an inputdisplay implemented with a plurality of such pixel unit. As the firstembodiment of the present invention, both of the pixel unit and theinput display are based on the TFT 40 shown in FIG. 4(b).

In FIG. 4(b), the TFT 40 includes at least a high-field electrode 401, alow-field electrode 402, a connecting section 403 for connecting thehigh-field electrode 401 and the low-field electrode 402, and a metallayer 409. The high-field electrode 401 is connected to the read-outline and the metal layer 409 is connected to the gate line 2. As FIG.4(b) shows, the connecting section 403 is mainly composed of anamorphous silicon layer 407 and the whole TFT 40 is fabricated on asubstrate 40′.

When the TFT 40 is switched OFF, a PN junction field occurs in afield-effect area 404 in part of the connecting section 403 near thehigh-field electrode 401. When the light is emitted to the field-effectarea 404, the electrons would be affected by the incident light and thePN junction field so that a photo-induced leakage current is generated.The object of the invention is to eliminate the photo-induced leakagecurrent.

The n-type TFT 40 is taken for example in FIG. 4, so the high-fieldelectrode 401 and the low-field electrode 402 can be defined as a drainterminal and a source terminal respectively while the gate terminal 409is at low voltage. If a p-type TFT, however, is taken for anotherembodiment of the present invention, then the high-field electrode 401and the low-field electrode 402 should be defined as a drain terminaland a source terminal respectively while the gate terminal 409 is athigh voltage. For one skilled in the art, the invention needs not belimited to the disclosed n-type TFT and is easy to be deduced in theapplications of the p-type TFT and the poly-TFT.

In the n-type TFT 40 shown in FIG. 4, the high-field electrode 401 andthe low-field electrode 402 are defined as a drain terminal and a sourceterminal respectively. There is a passivation layer 405 covering thehigh-field electrode 401, the low-field electrode 402 and the connectingsection 403. Besides, below the high-field electrode 401 and thelow-field electrode 402 are sequentially a N⁺ amorphous silicon layer406, an amorphous silicon layer 407, a gate insulator layer 408 and thegate terminal 409. There is further an indium-tin-oxide (ITO) layer 410covering the passivation layer 405 corresponding to the source terminal402. The ITO layer 410 is also connected to the metal layer 409 so as toconnect the low field electrode 402 to the metal layer 409. Theoperation of the low voltage is as described in FIG. 1 and will beomitted here.

According to the object of the invention, a light blocking layer isintroduced in order to eliminate the photo-induced leakage current. Inthe first embodiment of FIG. 4, a color filter (CF) 41 composed of afirst black matrix (BM) 411, a second BM 412, and a substrate 41′ isprovided. The first BM is adopted as the light blocking layer to hidethe field-effect area 404 from all incident light, so that the lightwill never emit to or through the field-effect area 404. Hence, thephoto-induced leakage current will be eliminated when the TFT 40 isswitched OFF, and the photo-induced ON current will still be hold whenthe TFT 40 is switched ON.

In the practical fabrication process, the width of the field-effect area404 is limited between 1 um and 5 um. Yet the key point of the firstembodiment is not the value of the width but is that the BM 411 shouldbe able to hide the field-effect area 404 from all incident lightperfectly, as shown in FIG. 4(b).

In the production process of a display, the defect of the shiftingbetween layers often occurs. For solving such a defect, in the presentinvention, the TFT 40 is implemented as the L-type structure shown inFIG. 4(a). The TFT structure 40 is set at an angle with respect to theelectric field of the PN junction. The angle in this embodiment is 90°.

Although the first embodiment is given in the application of an n-typeTFT, the present invention is still suitable for the application of ap-type TFT and a poly-TFT. Besides, it can also be utilized for thecombination of the fabrication process of a TFT-LCD to widen the utilityin the industrial application.

Please refer to FIG. 5 (a) and FIG. 5 (b). FIG. 5 (a) is an upper viewof an n-type TFT of a light detector array according to the secondembodiment of the present invention, and FIG. 5 (b) is a circuit diagramshowing the light detector array fabricated with the n-type TFT of FIG.5 (a). In FIG. 5 (a), the TFT 50 is in the area surrounded by data line1, data line 2, read-out line, gate line 1, and fixed voltage line whilethe remaining components in the area are omitted for the convenience ofillustration. The TFT 50 in FIG. 5 (a) is implemented to correspond tothe photo sensitive switch TFT 50 shown in FIG. 5 (b).

Similar to FIG. 4 (a) and FIG. 4 (b), the equivalent components aregiven the same symbols in FIG. 5 (a). To clarify the operation of theTFT 50 in FIG. 5 (a), the description will be given by referring to FIG.5 (b) firstly. In FIG. 5 (b), because the voltage level of the fixedvoltage line is lower than the voltage level (Vbias) of the read-outline, the TFT 50 is OFF and the body diode of the TFT 50 is reverselybiased. When the gate line 1 turns to high voltage, the current flowsfrom the fixed voltage line through read-out line 1 to the readoutamplifier 12.

The technical characteristic of this embodiment is also to adopt the BM511 as the light blocking layer to hide the field-effect area near thedrain terminal 501 from all incident light, so that the light will neveremit to or through the field-effect area. Hence, the photo-inducedleakage current will be eliminated when the TFT 50 is switched OFF, andthe photo-induced ON current will still be hold when the TFT 50 isswitched ON. However, the difference between FIG. 5 and FIG. 4(a) (orFIG. 4(b)) is that the source terminal 502 is not short-connected to thegate terminal 509 but is connected to the fixed voltage line as FIG. 5(a) shows. The drain terminal is still connected to the read-out line.

The n-type TFT 50 is taken for example in FIG. 5, so the high-fieldelectrode 501 and the low-field electrode 502 can be defined as a drainterminal and a source terminal respectively while the gate terminal 509is at low voltage. If a p-type TFT, however, is taken for anotherembodiment of the present invention, then the high-field electrode 501and the low-field electrode 502 should be defined as a drain terminaland a source terminal respectively while the gate terminal 509 is athigh voltage. For one skilled in the art, the invention needs not belimited to the disclosed n-type TFT and is easy to be deduced in theapplications of the p-type TFT and the poly-TFT.

Please refer to FIG. 6 (a) and FIG. 6 (b). FIG. 6 (a) is an upper viewof a TFT of a light detector array according to the third embodiment ofthe present invention, and FIG. 6 (b) is a circuit diagram showing thelight detector array fabricated with the TFT of FIG. 6 (a). In FIG. 6(a), the TFT 60 is in the area surrounded by data line 1, data line 2,read-out line, gate line 1, and fixed voltage line while the remainingcomponents in the area are omitted for the convenience of illustration.The TFT 60 in FIG. 6 (a) is implemented to correspond to the photosensitive switch TFT 60 shown in FIG. 6 (b).

Similar to FIG. 4 (a) and FIG. 4 (b), the equivalent components aregiven the same symbols in FIG. 6 (a). Although the technicalcharacteristic of this embodiment is also to adopt the BM 611 as thelight blocking layer to hide the field-effect area, the position of theBM 611 in FIG. 6 (a) is opposite to the position of the BM 511 in FIG. 5(a). That is, the BM 611 is fabricated to hide the high-field electrode601 which is connected to the fixed voltage line. The low-fieldelectrode 602 is still connected to the read-out line.

To clarify the operation of the TFT 60 in FIG. 6 (a), the descriptionwill be given by referring to FIG. 6 (b) firstly. In FIG. 6 (b), becausethe voltage level of the fixed voltage line is now higher than thevoltage level (Vbias) of the read-out line, the blocking fabrication ofthe BM 611 in FIG. 6 (a) is different from the blocking fabrication ofthe BM 511 in FIG. 5 (a).

The circuit implementation of the structure in FIG. 5 is shown in FIG.6. Compared with the circuit of the prior art shown in FIG. 1, the TFTsin FIG. 6 are controlled by a constant voltage.

Please refer to FIG. 7 (a) and FIG. 7 (b). FIG. 7 (a) is an upper viewof an n-type TFT of a light detector array according to the fourthembodiment of the present invention, and FIG. 7 (b) is a cross-sectionalview showing the structure of FIG. 7 (a) along the dotted line. In FIG.7 (a), the TFT 70 is in the area surrounded by data line 1, data line 2,read-out line, gate line 1, and gate line 2 while the remainingcomponents in the area are omitted for the convenience of illustration.The TFT 70 in FIG. 7 (a) is implemented to correspond to the photosensitive switch TFT 71 surrounded by gate line 1, gate line 2, andread-out line 1 shown in FIG. 1. In the upper view of FIG. 7 (a), only apart of the components of TFT 70 are shown. To clarify the structure ofthe TFT 70 of FIG. 7 (a), the description for FIG. 7 (b) is givenfirstly as follows.

The main object of the invention is to provide a pixel unit and an inputdisplay implemented with a plurality of such pixel unit. As the fourthembodiment of the present invention, both of the pixel unit and theinput display are based on the TFT 70 shown in FIG. 7 (b).

In FIG. 7 (b), the TFT 70 includes at least a high-field electrode 701,a low-field electrode 702, a connecting section 703 for connecting thehigh-field electrode 701 and the low-field electrode 702, and a metallayer 709. As FIG. 7 (b) shows, the connecting section 703 is mainlycomposed of an amorphous silicon layer 707 and the whole TFT 70 isfabricated on a substrate 70′.

When the TFT 70 is switched OFF, a PN junction field occurs in afield-effect area 704 in part of the connecting section 703 near thehigh-field electrode 701. When the light is emitted to the field-effectarea 704, the electrons would be affected by the incident light and thePN junction field so that a photo-induced leakage current is generated.The object of the invention is to eliminate the photo-induced leakagecurrent.

The n-type TFT 70 is taken for example in FIG. 7, so the high-fieldelectrode 701 and the low-field electrode 702 can be defined as a drainterminal and a source terminal respectively while the gate terminal 709is at low voltage. If a p-type TFT, however, is taken for anotherembodiment of the present invention, then the high-field electrode 701and the low-field electrode 702 should be defined as a drain terminaland a source terminal respectively while the gate terminal 709 is athigh voltage. For one skilled in the art, the invention needs not belimited to the disclosed n-type TFT and is easy to be deduced in theapplications of the p-type TFT and the poly-TFT.

In the n-type TFT 70 shown in FIG. 7, the high-field electrode 701 andthe low-field electrode 702 are defined as a drain terminal and a sourceterminal respectively. There is a passivation layer 705 covering thehigh-field electrode 701, the low-field electrode 702 and the connectingsection 703. Besides, below the high-field electrode 701 and thelow-field electrode 702 are sequentially a N⁺ amorphous silicon layer706, an amorphous silicon layer 707, a gate insulator layer 708 and ametal layer 709. There is further an indium-tin-oxide (ITO) layer 710covering the passivation layer 705 corresponding to the source terminal702. The ITO layer is also connected to the metal layer 709 so as toconnect the low-field electrode 702 to the metal. layer 709. Theoperation of the low voltage is as described in FIG. 1 and will beomitted here.

According to the object of the invention, a light blocking layer isintroduced in order to eliminate the photo-induced leakage current.Instead of the BM 411 in FIG. 4 (a), an additional layer 711 is providedin the fourth embodiment of FIG. 7. The additional layer 711 located onthe high-field electrode 701, which is composed of a opaque material,e.g. a kind of metal, is adopted as the light blocking layer to hide thefield-effect area 704 from all incident light, so that the light willnever emit to or through the field-effect area 704. Hence, thephoto-induced leakage current will be eliminated when the TFT 70 isswitched OFF, and the photo-induced ON current will still be hold whenthe TFT 70 is switched ON.

In the production process of a display, the defect of the shiftingbetween layers often occurs. For solving such a defect, in the presentinvention, the TFT 70 is implemented as the L-type structure shown inFIG. 7 (a). The TFT structure 70 is set at an angle with respect to theelectric field of the PN junction. The angle in this embodiment is 90°.

Although the fourth embodiment is given in the application of an n-typeTFT, the present invention is still suitable for the application of ap-type TFT and a poly-TFT. Besides, it can also be utilized for thecombination of the fabrication process of a TFT-LCD to widen the utilityin the industrial application.

In conclusion, an input display is provided in the present invention. Alight blocking layer, for example the black matrix 411 or the layer 711in the above-mentioned embodiments, is able to hide the PN field-effectarea near the high-voltage terminal from all incident light from theTFT. The incident light can not emit to or through the PN field-effectarea so that the photo-induced leakage current is eliminated when theTFT is switched OFF. The photo-induced ON current remains almostidentical when the TFT is switched ON, regardless of the presence of thelight blocking layer. The input display fabricated with the lightdetector array and the TFT provided in the present invention is able tobe fabricated in a higher aperture ratio and a higher production yield.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

1. An input display, comprising: a transistor comprising: a low-fieldelectrode; a high-field electrode connected to said low-field electrodewith a connecting section; and a field-effect area positioned on saidconnecting section and connected to said high-field electrode, wherein aPN junction field is formed in said field-effect area when saidtransistor is switched off; and a light blocking layer corresponding tosaid high-field electrode and hiding said field-effect area from allincident light from said transistor.
 2. The input display as claimed inclaim 1, wherein said transistor comprises a thin film transistor (TFT).3. The input display as claimed in claim 2, wherein said TFT comprises aN⁺ amorphous silicon layer, an amorphous silicon layer, a gate insulatorlayer, and a metal layer, and said connecting section comprises saidamorphous silicon layer.
 4. The input display as claimed in claim 3further comprising at least a gate line, wherein said metal layer isconnected to said gate line.
 5. The input display as claimed in claim 1further comprising a color filter (CF) and a passivation layer.
 6. Theinput display as claimed in claim 3, wherein an indium-tin-oxide (ITO)layer is formed to connect said low-field electrode and said metallayer.
 7. The input display as claimed in claim 1 further comprising atleast a fixed voltage line, wherein only one of said high-fieldelectrode and said low-field electrode is connected to said fixedvoltage line.
 8. The input display as claimed in claim 7 furthercomprising at least a read-out line, wherein said low-field electrode isconnected to said fixed voltage line while said high-field electrode isconnected to said read-out line and said low-field electrode isconnected to said read-out line while said high-field electrode isconnected to said fixed voltage line.
 9. The input display as claimed inclaim 5, wherein said light blocking layer is a black matrix (BM)located on a first side of said CF.
 10. The input display as claimed inclaim 9, wherein said high-field electrode has a side facing said CF andhaving a passivation layer formed thereon.
 11. The input display asclaimed in claim 10, wherein a photo-induced leakage current produced bya plurality of electrons influenced by said incident light and said PNjunction field in said field-effect area is eliminated because said BMhides said field-effect area.
 12. The input display as claimed in claim1, wherein said light blocking layer is located on said high-fieldelectrode.
 13. The input display as claimed in claim 12 furthercomprising a passivation layer formed between said light blocking layerand said high-field electrode.
 14. The input display as claimed in claim13, wherein a photo-induced leakage current produced by a plurality ofelectrons influenced by said incident light and said PN junction fieldin said field-effect area is eliminated because said light blockinglayer hides said field-effect area.
 15. A pixel unit, comprising: atransistor comprising: a low-field electrode; a high-field electrodeconnected to said low-field electrode with a connecting section; and afield-effect area positioned on said connecting section and connected tosaid high-field electrode, wherein a PN junction field is formed in saidfield-effect area when said transistor is switched off; and a lightblocking layer corresponding to said high-field electrode and hidingsaid field-effect area from all incident light from said TFT.
 16. Thepixel unit as claimed in claim 15, wherein said transistor comprises athin film transistor (TFT).
 17. The pixel unit as claimed in claim 16,wherein said TFT comprises a N⁺ amorphous silicon layer, an amorphoussilicon layer, a gate insulator layer, and a metal layer, and saidconnecting section comprises said amorphous silicon layer.
 18. The pixelunit as claimed in claim 17 further comprising at least a gate line,wherein said metal layer is connected to said gate line.
 19. The pixelunit as claimed in claim 15 further comprising a color filter (CF) and apassivation layer.
 20. The pixel unit as claimed in claim 17, wherein anindium-tin-oxide (ITO) layer is formed to connect said low-fieldelectrode and said metal layer.
 21. The pixel unit as claimed in claim15 further comprising at least a fixed voltage line, wherein only one ofsaid high-field electrode and said low-field electrode is connected tosaid fixed voltage line.
 22. The pixel unit as claimed in claim 21further comprising at least a read-out line, wherein said low-fieldelectrode is connected to said fixed voltage line while said high-fieldelectrode is connected to said read-out line and said low-fieldelectrode is connected to said read-out line while said high-fieldelectrode is connected to said fixed voltage line.
 23. The pixel unit asclaimed in claim 20, wherein said light blocking layer is one selectedfrom a group consisting of a black matrix (BM) located on a first sideof said CF and a layer located on said high-field electrode.
 24. Anelimination method for a photo-induced leakage current of an inputdisplay, comprising steps of: providing a transistor comprising alow-field electrode, a high-field electrode connected to said low-fieldelectrode with a connecting section, and a field-effect area positionedon said connecting section and connected to said high-field electrode;and hiding said field-effect area from all incident light from said TFTso that said photo-induced leakage current produced by a plurality ofelectrons influenced by said incident light and said PN junction fieldformed in said field-effect area when said transistor is switched off iseliminated.
 25. The elimination method as claimed in claim 24 furthercomprising the step of: forming a black matrix (BM) located on a firstside of a CF to hide said field-effect area from all incident light fromsaid transistor.
 26. The elimination method as claimed in claim 24further comprising the step of: forming a light blocking layer locatedon said high-field electrode to hide said field-effect area from allincident light from said transistor.